The invention relates to a ventilation device for the interior of a motor vehicle having means for switching between a recirculation air mode and a fresh air mode, and a method for ventilating the interior of a motor vehicle.
Heretofore, the wash water spray nozzles for the cleaning unit for the windshield of a motor vehicle have always been located in the vicinity of the air intake for the ventilation, i.e., air conditioning system. As a result, when the cleaning unit is actuated the air intake region of the ventilation or air conditioner system is wetted by the wash water, and thus by the cleaning additives contained therein and emitted therefrom. This is also a problem when the washer unit for the headlights is actuated, since, depending on the travel speed, the wash water likewise more or less wets the windshield or the air intake region of the ventilation or air conditioner system. Because both cleaning units are generally actuated together in a cyclical manner, the wetting effect is further intensified. Known ventilation devices for motor vehicle ventilation or air conditioner systems either draw the air which is wetted with wash water additives into the interior of the vehicle, or when the cleaning unit is actuated switch from fresh air mode to recirculation air mode, in which fresh air is no longer drawn in from the outside.
A generic ventilation device is known from German patent document DE 38 13 548 A1. This ventilation device avoids drawing in the gases, which are generated from the wash water exiting from the windshield washer nozzles in the fresh air intake region, by closing the fresh air valve and switching the ventilation device to recirculation air mode when the wash water spray nozzles are actuated. After a predeterminable residence time the system automatically switches back to fresh air feed.
Furthermore, a device is known from European patent document EP 0 330 827 A1 in which the fresh air feed to the interior of the motor vehicle is likewise interrupted when the windshield washer unit is actuated, and is resumed after a predeterminable time.
In the devices according to the prior art, it is disadvantageous that within the residence time for recirculation air mode, condensation can form on the glass which impairs safety, forcing the driver to perform a manual intervention, deactivate the recirculation air, and turn on the defroster function. This causes the driver to be unsafely distracted from the traffic situation.
An object of the invention is to provide a ventilation device of the aforementioned type which minimizes the load of fresh air drawn in, along with detergent additive gases generated by actuation of the windshield washer, and which also further increases the safety in control of the vehicle.
This object is achieved by a ventilation device which switches between a recirculation air mode and a fresh air mode, comprising at least one condensation sensor for determining at least one parameter reflecting the degree of glass condensation or probability of glass condensation, and at least one evaluation device. In one embodiment, the evaluation device as a function of this/each determined parameter generates a signal for at least temporarily switching to fresh air mode when a parameter limiting value exceeds a predefined value. Alternatively, for generating a signal for the fresh air-recirculation air switching, one further embodiment provides for the generation or determination of a time period for a residence time to be observed in recirculation air mode. According to the invention, it is possible to effectively prevent condensation on the glass of a motor vehicle which impairs driving safety by detecting at least one parameter for the condensation present on the glass, using a condensation sensor, and evaluating the detected parameter using an evaluation device, and indirectly or directly actuating a closing device for switching to recirculation air mode using a control device. Actuation of the cleaning unit initiates a signal for closing the closing device and thus for switching to recirculation air mode. Then, by use of the evaluation device and the control device the closing device is indirectly or directly actuated as a function of the degree of probability of glass condensation (indirect actuation) or condensation actually present on the glass (direct actuation).
The indirect actuation is achieved by detecting and evaluating beforehand at least one parameter of glass condensation which is actually not visible and is thus being formed (e.g., air moisture and/or inside temperature and/or outside temperature) for the probability of glass condensation. In other words, before visible condensation on the glass is even present, a reliable prediction may be made as to when the glass is likely to have condensation such that safety in controlling the vehicle is impaired due to poor visibility caused by glass condensation. Based on this prediction, an appropriate decision may then be made as to when the ventilation device should be switched from recirculation air mode to fresh air mode or partial fresh air mode (mixed mode) to reliably avoid condensation on the glass. To avoid the transport of moist air to the glass, in an intermediate step before switching from recirculation air to fresh air mode it is possible to prevent air feed to the glass (fresh air feed in the vehicle interior but not in the glass region) to delay the formation of condensation or, alternatively, to extend the residence time in recirculation air mode.
The direct actuation of the closing device for switching from recirculation air mode to fresh air mode is achieved by detecting and evaluating at least one parameter for determining glass condensation which is actually already visible (e.g., air moisture and/or inside temperature and/or outside temperature). In this case, visible condensation on the glass is thus already present (the parameter to be detected and evaluated has therefore already exceeded a predefined parameter limiting value), on the basis of which a switch from recirculation air mode to fresh air mode is directly made.
In both cases (indirect or direct actuation) the switch may be made from 100% recirculation air mode to 100% fresh air mode. In one preferred embodiment, a phased transition from recirculation air mode to fresh air mode is provided, the switch from recirculation air mode to fresh air mode being made by continuous or steplike opening or closing of the closing device.
For the switch to recirculation air mode initiated by actuation of the cleaning unit, hardware and/or software are provided which enable the activation of the wash water spray nozzles to be temporarily delayed. When activation of the wash water spray nozzles is delayed, the closing device for recirculation air mode is temporarily brought into the closed position before the wash water spray nozzles are activated. For an undelayed activation of the wash water spray nozzles, the closing device and wash water spray nozzles are actuated simultaneously. Switching between these two operating modes can be achieved manually, using a switch, or automatically as a function of boundary parameters (e.g., outside air moisture and/or outside air temperature and/or outside air contaminants).
The invention further relates to a method for ventilating the vehicle interior, using the device according to the invention, in which, initiated by actuation of the cleaning unit, a signal for closing the closing device (switching to recirculation air mode) is generated and at least one parameter for a degree of glass condensation or the probability of glass condensation is determined, and as a function of each determined parameter, either a signal is generated for directly opening the closing device and thus for switching, at least in some areas, to fresh air mode by comparing to a predefined limiting value, or an indirect opening is initiated by determining a time period to be observed for the closed position of the closing device, and after this time period has elapsed the closing device is opened at least in some areas. In this regard, the signal generation for actuating the wash water spray nozzles and the signal generation for closing the closing device may be achieved either simultaneously or successively (closing of the closing device and subsequent activation of the wash water spray nozzles). Switching between these two operating modes may be accomplished either manually, using a switch, or automatically as a function of boundary parameters (e.g., outside air moisture and/or outside air temperature and/or outside air contaminants).
The layout of the sensor(s) according to design and type depends on the parameter variable(s) to be detected. Thus, in particular the use of an air moisture sensor alone or in combination with an outside and/or inside temperature sensor is possible. In addition, the previous progression over time of these variables may be of interest for a decision as to whether recirculation or fresh air mode is necessary, and therefore included in the evaluation of the parameters. Consequently, these variables could be continuously detected when the cleaning unit is not actuated or the vehicle is not operating, and in each case data stored in a time window, so that upon start-up of the vehicle or actuation of the cleaning unit after a period of not being actuated these data may be accessed via an evaluation device, and based on instantaneous data, actuation may be achieved directly after initiation using an actuation device for recirculation air-fresh air. Both the evaluation device and the actuation device are preferably integrated into the engine control unit or a control device which monitors the control function of the air conditioning system. In particular, these devices may be incorporated in the form of programming into the existing resources of standard control devices already in use (e.g., air conditioning controls). The evaluation and actuation devices are designed in such a way that the switch to recirculation air mode is either initiated or terminated after activation of the cleaning unit but temporarily before an actual spray function of a wash water spray nozzle, or the spray function and switch to recirculation air mode are initiated essentially at the same time. The temporarily delayed switch to recirculation air has the advantage that, as the result of activation of a wash nozzle and the subsequent switch from fresh air to recirculated air, there is increased assurance that interfering gases from the washer fluid do not enter the interior of the vehicle.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.